F Units-United States Collection of various schemes throughout the US Uses Jointed Rail's F7 model. Trainz Forge is a dedicated team of Trainz content artists who strive to bring the community the best content available. Originally known as TrainzPA, we have rapidly evolved to become one of the hardest working teams in 3rd party creation. As we grow as a team, we will bring you even more content that pushes the boundaries of our ability.
In 1939 General Motors Electro - Motive Division issued a challenge to the supremacy of steam traction with the introduction of the FT class.
Although proven as capable traction for passenger traffic, many were sceptical of the ability of diesels to haul freight. GM launched an 11 month tour of 35 states and 20 Class 1 railroads demonstrating the advantages of such a locomotive.
The FT class (F for freight T for 2700 hp with b-unit) proved a force to be reckoned with, hauling more freight, for less fuel and with less maintenance than any steam locomotive. Several units could be used on a train to meet horsepower requirements; this ability to 'lash' several units together, meant that a single crew could operate them via multiple unit controls.
In all, over 7600 F units (both A units and boosters) were built between 1939-1960. The FT was followed by the F2, F3, F7, FP7, F9, FP9, and production ended in 1960 with the FL9.
The F was easily the top selling cab unit of all time, and ushered in a more colourful era in the history of railroads, with several operators adourning the art decco style carbodies with flamboyant liveries, such as the world famous Santa Fe 'warbonnet' scheme. The f7 was the most numerous.
Although designed for freight, f-units were widely used on passenger services, many being fitted with boilers for passenger car heating systems. These units carried up to 100 gallons of water for this purpose.
There are only two models to have outsold the f7, both are also EMD units - the GP9 and SD40-2 hood units, though none have imparted such an impression as the world famous f7.Resources
F7 Ustrainz Forged
F7 Gallery - Northeast Railfan.Net - EMD diesel trains
F Units - by Barry Silverthorn
ATSF Resources - Q Station
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F7 Us Trainz Forge 1.12.2
62:15 became the 'standard' freight gear ratio, and units with it were permitted 70 MPH, with the Overspeed feature set at about 72.
60:17 was the 'standard' passenger gear ratio, and those units were permitted 79 MPH, with the Overspeed set at about 83.
Both the 70 and 79 limits were higher than those recommended by EMD, but apparently SP never had any problems.
Many SP-family F units were delivered with slower 65:12 (55 MPH) gearing for freight service, or with higher 61:16 (71 MPH) gearing. Most, if not all, were converted to either the 62:15 or 60:17 gearing noted above.
Over on the Santa Fe, in 1961 the 16, 37 and 300 Classes were permitted to operate at 100 MPH, the 325 Class 80 MPH, and the 100 and 400 Classes 65 MPH. Sorry, but I'm not familiar with the gearing they used, but I suspect the 80 MPH would be 60:17 and the 65 MPH 62:15.
I don't have anything specific for Union Pacific units, but a 1956 South Central District (LA&SL) timetable simply listed the maximum speed for passenger trains as 79 and for freight trains as 60, so you can draw your own conclusions.
And finally, the last timetable I have for the Rock Island, issued March 18, 1979, lists two F7A's, 675 & 676, as being allowed 95 MPH. All of the Rock's freight F-units has bit the dust by that time.